There are many applications of automated systems used for the testing of telecommunication systems and devices attached to telephone lines. These automated telephone tester systems launch telephone calls to the telecommunication system under test to exercise certain capabilities and/or validate the proper operation of the system under test by determining the responses to the telephone test call sequence of stimulus or inputs. Changing conditions or errors in the system under test may cause that system to play different speech audio than is expected in response to each step of a testing sequence. For example, an automated test call into a telephone banking system might dial the telephone access number, determine that the expected speech audio greeting and prompt is played within a few seconds, dial additional DTMF (touch tone) digits to input an account number, determine that the expected speech audio response is played within a few seconds, and so forth.
The telephone-related systems that are typically tested with automated testers include Private Branch Exchange (PBX) systems, Automatic Call Distribution (ACD) systems, telephone company Central Office (CO) telephone switching systems, voice messaging systems, call prompting systems, telephone debit card systems, international telephone callback systems, telephone network call routing control systems, interactive voice response systems, voice processing systems, call-back messaging systems, facsimile processing systems, telephone modems, predictive dialing systems, and combinations of such systems that may be known as computer-telephone integration (CTI) arrangements. These CTI arrangements may provide functions like inbound or outbound call screen pop to coordinate the delivery of telephone calls with computer display screen of relevant information, coordinated call/screen transfer, control of telephone functions from a computer workstation or server, consolidation of management reporting information from two or more telephone-related systems, and so forth.
The telephone test call connections may be direct and local in the same room or through a public or private telephone communication network. Verification of features, functions, interfaces, integrations, capacities, and availability are among the typical objectives of a testing process. As the services these systems provide become more important to business success and the custom integrations become more complex, the requirements for definitive automated validation testing increases proportionately. The use of these automated testers is particularly important when the test is designed to validate the capacity of the system under test to monitor, control, respond to, handle, or track the results of telephone call traffic.
These automated telephone tester systems have several things in common. The automated testers are microprocessor based. Multi-tasking of the microprocessor is required to launch, control, and store information about multiple simultaneous telephone test calls, so they make use of a multi-tasking operating system such as Windows NT, UNIX, or some proprietary operating system. These automated testers typically include one or more hardware interfaces to multiple telephone lines for launching or receiving telephone test calls. These automated testers have some means of defining and storing the test call sequences of stimulus, inputs and other parameters. These test call sequences typically include the telephone number to be dialed, subsequent additional DTMF or MF (multi-frequency) or rotary dial digits to be dialed, other tones to be transmitted on the test call and so forth. More advanced testing systems also offer capabilities to offer inputs by playing recorded speech files in lieu of dialing DTMF digits.
A capability of any telecommunications tester is found in the determination of how and when a test call makes its way through a telephone network and is answered by the system under test. The general term for this determination is call progress detection. This term refers to the determination of things like dial tone, busy tone, ring-back tone, SIT tri-tones, DTMF (touch tone) digit tones, periods of silence, answer detection, and on-hook detection. Current telephone testing systems generally make use of telephone interface hardware from a manufacturer like Dialogic Corporation, Natural Microsystems, or Rhetorix. These testing systems rely upon the call progress detection techniques made available by the manufacturer of the telephone line interface hardware.
The art of call progress detection is based upon sensing one or more audio frequencies for specific periods of time. For example, North American standard dial tone is a simultaneous combination of 350 Hertz and 440 Hertz tones with extended duration of several seconds. North American standard station busy tone is a combination of 480 Hertz and 620 Hertz tones with a duration of 500 milliseconds, followed by silence for 500 milliseconds, followed by the combined tones for 500 milliseconds, and so forth. North American standard telephone network congestion busy tone uses the same combination of 480 Hertz and 620 Hertz tone frequencies with 250 millisecond duration of the tone and silence periods. Other call progress tones use specific frequencies and patterns of tone alternating with silence. Answer detection is generally based upon the detection of audio with frequency components that are characteristic of human speech, the cessation of a ring-back tone sequence, or an electrical or signaling condition change on the calling telephone line.
FIG. 3A shows the progress of a typical telephone test call. At T0, the destination telephone number has been dialed. At T1, the ring-back tone sequence begins with a period of audio. At T2, the first ring-back tone audio period ends. At T3, the second ring-back tone audio period begins. At T2, most call progress detection methods will determine that a ring-back tone sequence is in progress. At T4, the second ring-back tone audio period ends. At T5, speech audio begins as the call is answered and a greeting is played.
Another key capability of any telecommunications tester is found in the determination of how and when the system under test responds on the telephone line to the sequence of stimuli or inputs being generated during each test call. More advanced testing systems may offer capabilities for direct or LAN data communication with the system under test to determine other information about responses to the telephone test calls. With the widespread use of voice response technology, the validation testing of many telephone-related systems requires one or more determinations that certain speech audio phrases are played by the system under test at specific points of a test call sequence. The Hammer.RTM. telecommunication system tester determines that specific speech phrases have been played by means of voice recognition technology and methods as defined in U.S. Pat. No. 5,573,570 (Kuenzig). One shortcoming of the Kuenzig Patent is that voice recognition technology is costly to equip in a testing system. Another shortcoming of the Kuenzig Patent is that voice recognition techniques may be adversely affected by noise and other conditions on telephone lines.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for testing system for telecommunications systems that overcomes the problems identified above.